1. Field of the Invention
The present invention relates generally to photocopying machines and more specifically to a photocopying machine with an improved source of illumination.
2. Description of the Prior Art
Photocopying machines of the kind where documents are laid on a copying surface normally require the documents to be illuminated. An example of such a machine is a microfiche camera.
Known microfiche cameras have illumination provided from lamps carried on arms so as to be at some distance from the copying surface. The lamps have to be positioned in relation to the copying surface so that light from the lamps is not regularly reflected by the document being copied into the camera lens. At the same time, it is also desirable to have illumination as near to the normal of the copying surface as is possible. These two requirements result in practice in the incident light from the lamps being at an angle of around 45.degree. to the copying surface.
If the lamps are set too close to the document, the distance from the lamp to one edge of the document is considerably different to the distance to the other edge. Thus, the light intensity varies over the width of the document. To obviate this disadvantage, the lamps are set as far as practical from the document, thus ensuring as even an intensity over the surface of the document as possible. The disadvantage in this case is that the copying machine becomes cumbersome and the lamps on their arms are vulnerable to damage.
If the light from the lamps is required to be filtered, each lamp would have to be provided with a filter to overcome the disadvantages and to provide a more convenient lighting arrangement.